[vc_row][vc_column width=“1/1″][vc_column_text]What is the potential of measuring the enantiomeric ratio of drugs using supercritical fluid chromatography–MS?[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Maria Kristina Parr, Alexander H Schmidt,
Bioanalysis 6 (2014) 3267-3270.[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]“Supercritical fluid chromatography allows fast and efficient separation of enantiomers.”
Analytical chemists are always looking for more efficient techniques to meet analytical challenges of today’s regulatory and scientific requirements. One technique that has made drastic improvements in recent years is supercritical fluid chromatography (SFC).[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]UHPLC Method Development and Modelling in the Framework of Quality by Design[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Imre Molnár, Alexander H Schmidt, H-J Rieger, J. Fekete, R. Kormany
TheColumn, April 2014[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]The goals in ultrahigh-pressure liquid chromatography (UHPLC) method development are to first find the best separation, second find the best column, and third find the most robust method in a multifactorial Design Space. Trial and error methods are not sufficient anymore and solid science based on Quality by Design (QbD) principles is required.[/vc_column_text][vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Rapid UHPLC Method Development for Omeprazole Analysis in a Quality-by-Design Framework and Method Transfer to HPLC using Chromatographic Modeling[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt, Mijo Stanic
LCGC North America, 32 , No 2 (2014) 126-148[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]The aim of this study was to apply quality-by-design principles to build in a more scientific and risk-based multifactorial strategy in the development of an ultrahigh-pressure liquid chromatography (UHPLC) method for omeprazole and its related impurities[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]In silico robustness testing of a compendial HPLC purity method by using of a multidimensional design space build by chromatography modeling–Case study pramipexole[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt, Mijo Stanic, Imre Molnár
Journal of Pharmaceutical and Biomedical Analysis 91 (2014) 97-107[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]Purity testing of pramipexole is performed using an official (compendial) and harmonized method published in the European Pharmacopoeia (E.P.) and United States Pharmacopoeia (USP). According to this monograph the successful chromatographic separation of the API from impurities is achieved on a C18 column with gradient elution of an ion pairing buffer of pH 3.0 (mobile phase A) and acetonitrile (mobile phase B). Although not recommended in general, compendial methods are often adapted for purity testing of generic formulations. In this paper a novel approach to evaluate method robustness of an adapted method – prior of full method validation – is described. Based on Quality-by-Design (QbD) principles, a small number of experiments are performed, which after entering them into a chromatography modeling software allow to visualize a multidimensional “Design Space”, a region, in which changes in method parameters will not significantly affect the results as defined in the ICH guideline Q8(R2) leading to a more flexible method handling in routine analysis. For two different recommended C18 columns a multidimensional Design Space (Method Operating Design Region, MODR) was constructed to study the robustness of the adapted method with a newly developed Robustness Module. In a full factorial design the following six parameters were varied at three levels (low, nominal, high): Gradient time, temperature, pH of the aqueous eluent (A), flow rate, start- and end concentration of the organic mobile phase component (eluent B). The resulting 3^6 = 729 experiments were performed in silico from the previously constructed models for Design Space in less than 1 min and showed that the required resolution of 2.0 could not be reached in all experiments for the two columns which were recommended by the E.P. (failure rate 25% and 16%, respectively). However, by adjusting the gradient time, we were able to fulfill the requirements with a failure rate of zero…..[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]A QbD with Design-of-Experiments approach for development of a state-of-the-art UPLC purity method for carbamazepine[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt, Carsten Wess
Journal of Liquid Chromatography & Related Technologies 37 (2014) 2653-2666[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]A state-of-the-art ultra-performance liquid chromatographic (UPLC) method has been developed for purity testing of carbamazepine. Successful chromatographic separation of the active pharmaceutical ingredient (API) from its impurities was achieved on a WATERS ACQUITY UPLC CSH C18 column with the dimensions 2.1 mm x 100 mm and 1.7 µm particle size with gradient elution of 0.2% phosphoric acid and acetonitrile in only 5 min. Incorporating Quality by Design (QbD) principles to the method development approach by using the statistical software package Fusion AE allows to study the relationship between chromatographic parameters (factors) and the resolution (response) between the peaks of interest. In a screening phase the factors known to have major effect in column selectivity (stationary phase, pH of the aqueous eluent, organic eluent type, gradient time and slope) are studied. In the second phase the chromatographic parameters identified to affect the resolution are studied with additional instrument settings. In both phases statistical concepts with experimental design plans (Design-of-Experiments) are used as an efficient and fast tool to simultaneously gain knowledge about the influencing factors and interactions. An operating space within the design space is established and a verification study confirms the robustness of the final method. Total analysis time is only 5 min, which is an impressive 22-fold increase in productivity in comparison to the method published in the European Pharmacopeia.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Using an innovative Quality-by-Design approach for development of a stability indicating UHPLC method for ebastine in the API and pharmaceutical formulations[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt, Imre Molnar
Journal of Pharmaceutical and Biomedical Analysis 78-79 (2013) 65-74[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]A stability-indicating ultra high performance liquid chromatographic (UHPLC) method has been developed for purity testing of ebastine and its pharmaceutical formulations. Successful chromatographic separation of the API from impurities was achieved on a Waters Acquity UPLC BEH C18, 50 mm × 2.1 mm, 1.7 μm particle size column with gradient elution of 10 mM acetate buffer pH 6.2 and a mixture of acetonitrile/2-propanol (1:1) as the mobile phase. Incorporating Quality by Design (QbD) principles to the method development approach by using the chromatography modeling software DryLab®4 allows the visualization of a “Design Space”, a region in which changes to method parameters will not significantly affect the results as defined in the ICH guideline Q8 (R2). A verification study demonstrated that the established model for Design Space is accurate with a relative error of prediction of only 0.6%. The method was fully validated … The robustness of the developed method was studied by varying the six parameters: gradient time, temperature, ternary composition of the eluent, flow rate and start and end concentration of the gradient at 3 levels (+1, 0, −1). The resulting 729 experiments were performed in silico from the previously constructed model for Design Space and showed that the required resolution of 2.0 can be reached in all experiments. To prove the stability-indicating performance of the method, forced degradation (acid and base hydrolysis, oxidation, photolytic and thermal stress conditions) of ebastine was carried out. Baseline separation could be achieved for all peaks of the impurities, the degradation products and the API. Total run time was only 4 min, which is an impressive 40-fold increase in productivity in comparison to the method published in the Ph. Eur. monograph and allowed purity testing of more than 360 samples per day.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text] UPLC-MS/MS in support of cleaning validation studies in an cephalosporin antibiotics production facility[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt, Mijo Stanic
G.I.T. Laboratory Journal Europe 5-6/2012[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]Pharmaceutical manufacturing equipment has to be cleaned after production in order to avoid cross contamination in the next batch of a different product. The effectiveness of the cleaning process should be confirmed by cleaning validation studies. An ultra-performance liquid chromatography method with tandem-MS detection (UPLC-MS/MS) was developed for the simultaneous determination of residues of the following beta-lactam ring containing cephalosporin antibiotics on swabs collected from pharmaceutical manufacturing equipment surfaces: cefuroxime axetil (R) and (S) isomers; cefuroxime, cefixime; cefaclor; cefpodoxime proxetil (R) and (S) isomers; cefalexin, cefadroxil[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Transfer of USP-based HPLC Methods for Pantoprazole Sodium to UPLC – 20-fold increase in productivity[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt
G.I.T. Laboratory Journal Europe 9-10/2010[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]HPLC is a commonly used analytical method for assaying and purity controlling of active pharmaceutical ingredients („API’s”) in the pharmaceutical industry. Method transfer to the latest technologies can be time-consuming and are therefore rarely performed for the improvement of validated methods. However, the transfer of established methods to a UPLC (ultra performance liquid chromatography) system can be worth the investment. In the reported case such an investment was rewarded with surprising savings in analysis time, operational costs and improved resolution. We demonstrate the successful method transfer for the analysis of pantoprazole sodium from the USP-recommended L1 column, run on a conventional HPLC system, to a sub 2 µm particle column on a UPLC system. With some small optimization changes, the final methodology reduced the analysis run time from 55 min with HPLC to just 3 min with UPLC, resulting in a 20-fold increase in throughput and a remarkable reduction in solvent consumption and waste disposal costs[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Validated HPLC Method for the Determination of Residues of Acetaminophen, Caffeine, and Codeine Phosphate on Swabs Collected from Pharmaceutical Manufacturing Equipment in Support of Cleaning Validation[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt
Journal of Liquid Chromatography & Related Technologies Volume 29, Issue 11, 2006, pages 1663-1673[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]A high performance liquid chromatography (HPLC) method was developed for the simultaneous determination of residues of acetaminophen (paracetamol), caffeine, and codeine phosphate on swabs collected from pharmaceutical manufacturing equipment surfaces. Any residues of the compounds remaining on process equipment after cleaning are removed by swabbing with wet Texwipe® swabs, premoistened with methanol/water, followed by dry Texwipe® swabs. These residues are extracted from the swabs by means of an ultrasonic bath and the amounts of the compounds are determined. The chromatography was performed in the isocratic mode on a RP‐18 column using a mobile phase consisting of 25 mM ortho‐phosphoric acid and acetonitrile (90:10, v/v). UV‐ and fluorescence detection was performed in order to improve the method’s sensitivity. The method was validated by specificity, linearity, limit of detection, and limit of quantification, accuracy, and precision for the residues of acetaminophen (paracetamol), caffeine, and codeine phosphate on equipment surfaces. Stability studies have demonstrated the stability of the residual active compounds on equipment surfaces and on the swabs.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Development of an HPLC Method for the Determination of Hydroxycinnamic Acid Derivatives in Cimicifuga racemosa (Black Cohosh) Extracts Using an Automated Method Development System [/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt
Journal of Liquid Chromatography & Related Technologies Volume 28, Issue 6, 2005, pages 871-881[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]The separation of a complex mixture, such as the ingredients in medicinal plants, is typically difficult and the development of a HPLC method is a labor‐intensive and time‐consuming process if carried out manually. Automation of this process can increase productivity of a pharmaceutical R&D department substantially. This paper describes the development of a high performance liquid chromatographic method for the determination of hydroxycinnamic acid derivatives in Cimicifuga racemosa extracts and its preparations by using a fully automated method development system (Waters AMDS). The developed method is based on the baseline chromatographic separation of six hydroxycinnamic acid derivatives (caffeic acid, ferulic acid, isoferulic acid, fukinolic acid, cimicifuga acid A, and cimicifuga acid B), the major constituents in Cimicifuga racemosa (Black Cohosh), on a XTerra MS C18 column with a water‐methanol gradient and photodiode array detection.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Computer-assisted optimization in the development of a high-performance liquid chromatographic method for the analysis of kava pyrones in Piper methysticum preparations[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt, Imre Molnar
Journal of Chromatography A, 948 (2002) 51-63[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]A computer simulation program was used to optimize the separation for six kava pyrones and two unidentified components obtaining the best resolution and the shortest run time. With DryLab it was possible to find the best separation conditions without running a large number of possible combination of variables in the laboratory. Additionally, due to the systematic progress in method development a new eluent was found with excellent properties, namely 2-propanol. With 2-propanol, the largest number of components could be revealed in the shortest analysis time. Starting with four initial experiments, the software allowed to optimize gradient time tG and temperature T simultaneously. Changing other variables such as type of organic modifier, the eluent pH, the gradient form, and the flow-rate, the optimization resulted in resolution Rs>1.5 for all kava pyrones and the two additional new bands. The HPLC method is used to analyze kava pyrones in Piper methysticum preparations[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Use of an on-line, precolumn photochemical reactor in high-performance liquid chromatography of naphthodianthrones in Hypericum perforatum preparations[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt
Journal of Chromatography A, Volume 987, Issues 1–2, 14 February 2003, Pages 181-187[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]A method has been developed for the determination of naphthodianthrones in Hypericum perforatum L. extracts and phytopharmaceutical preparations by high-performance liquid chromatography combined with on-line, precolumn photochemical conversion followed by photodiode-array detection. The chromatographic separation was performed on a C18 column under isocratic reversed-phase conditions. An on-line, precolumn photochemical reactor equipped with a knitted PTFE reaction coil around a visible light source was used in order to transform the light sensitive naphthodianthrones, protohypericin and protopseudohypericin, very easily into the non-protoforms, hypericin and pseudohypericin, respectively. Two UV chromatograms (photochemical reactor “on” and “off”) were compared and were quite useful in characterizing the sample. Validation studies demonstrated that this HPLC method is simple, rapid, reliable and reproducible. The time-consumptive manual irradiation of the samples is omitted by this automated on-line irradiation step. The developed method was successfully applied to the quality control of Hypericum perforatum L. extracts and its phytopharmaceutical preparations[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Fast HPLC for quality control of Harpagophytum procumbens by using a monolithic silica column: method transfer from conventional particle-based silica column[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt
Journal of Chromatography A, Volume 1073, Issues 1–2, 6 May 2005, Pages 377-381[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]The applicability of a monolithic C18-bonded silica column for the rapid HPLC separation of ingredients in medicinal plants and their phytopharmaceutical preparations has been evaluated in the author’s laboratory. In this presentation, an existing method for the determination of the iridoid glycoside harpagoside in Harpagophytum procumbens (Devil’s Claw) was successfully transferred from a conventional particle-based C18 silica column to a monolithic silica column. The very high porosity of the stationary phase allows chromatography with a much lower backpressure than on conventional columns. Therefore, the flow rate could be easily increased from 0.8 mL/min (particle-based column) to 5 mL/min (monolithic column) and the run-time reduced from 30 to 5 min (that is a reduction about 85%!), without losing any chromatographic resolution of the compound of interest. The amount of harpagoside was measured with the original method on a conventional particle-based silica column and on the adapted method on a monolithic silica column. The statistical mean t-test showed no significant differences of the variances and the means indicating that the fast HPLC method is an acceptable alternative. The shorter analysis time makes the method very valuable for commercial quality control of Harpagophytum extracts and its pharmaceutical preparations[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/1″][vc_column_text]Validation of A Fast‐HPLC Method for the Separation of Iridoid Glycosides to Distinguish Between the Harpagophytum Species[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=“1/4″][vc_column_text]Alexander H Schmidt
Journal of Liquid Chromatography & Related Technologies Volume 28, Issue 15, 2005, pages 2339-2347[/vc_column_text][/vc_column][vc_column width=“3/4″][vc_column_text]A fast high‐performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of the iridoid glycosides harpagoside (HS) and 8‐p‐coumaroyl‐harpagide (8pCHG) in extracts and preparations of Harpagophytum procumbens and H. zeyheri. The ratio between 8pCHG and the sum of HS and 8pCHG can be used to distinguish between both species. Quantitation was accomplished with the internal standard (IS) method. The separation was performed on a monolithic silica column (Chromolith Performance RP‐18e), under gradient conditions using a mobile phase of water (pH 2.0 adjusted with phosphoric acid) and acetonitrile. The elution of the analytes was monitored at 278 nm and conducted at a column temperature of 30°C. Because of the high porosity of the monolithic column the mobile phase was able to be pumped at a flow rate of 5.0 mL/min. The retention time of 8pCHG, HS, and the IS was 1.9 min, 2.1 min, and 3.0 min, respectively, and the total run time of the assay was 5 min. The method was validated by specificity, linearity, accuracy, and precision. For the determination of method robustness a number of chromatographic parameters were varied.[/vc_column_text][/vc_column][/vc_row]